Two temperature refrigerator, including a humidity control system



Jam 3, 1950 w. D. JORDAN ETAL 2,493,488

TWO-TEMPERATURE REFRIGERATOR, INCLUDING A HUMIDITY CONTROL SYSTEM FiledMarch 21, 1945 3 Sheets-Sheet 2 @PMA m Jan. 3, 1950 w. D. JORDAN ET AL2,493,488

TWO-TEMPERATURE REFRIGERATOR, INCLUDING A HUMIDITY CONTROL SYSTEM FiledMarch 2l, 1945 l 3 Sheets-Sheet 3 bij Patented Jan. 3, 1950 TWOTEMPERATURE REFRIGERATOR, IN- CLUDING A HUMIDITY CONTROL SYSTEM Wayne D.Jordan, Chicago. and Paul D. Van

Vliet, Galesburg, Ill., assgnors to Liquid Carbonc Corporation, Chicago,Ill., a corporation of Delaware Application March` 21, 194,5, Serial No.583,924 v (Cl. 621l6) 8 Claims. l

This invention relates to an improvement in. refrigerators and isadapted Yfor use in donlestlo` refrigerators.

One purposeI isY to provide an improved. two temperature refrigerator.

Another purpose is .tol provide a two temperature refrigerator having'separate refrigerating means for a relatively high temperature and alow temperaturestorage space, the Storage spaces being separate, andinsulated.

Another purpose is to provide improved means for controlling therelative humidity Of air in a refrigerator storage cabinet.

Another purpose is to provide improved means for freezing ice cubes andfor at the same timev controlling the relative humidity of arefrigerator storage cabinet.l

vAnother purpose is to provide a refrigerator cabinet having means forfreezing ice cubes in a relatively high temperature storage spacewithout unduly dehydrating the foods in such storage space.

Another purpose is-to'provide a means of and method Yfor employing icecube freezing means to control the relative humidity of a refrigeratorstorage space in which food is stored at temperatures above freezing.

Another purpose is to provide means for preventing excess humidity in arefrigeration storage cabinet in which the food is stored attemperatures above freezing.

Other purposes will appear from time to time in the course ofthe'specication and claims.

The invention 'is illustrated more or less diagrammatically yin Y theaccompanying drawings wherein:

Figure 1 is a vertical section of a two temperature refrigerator; 1

Figure 2 is a section at the line 2--2 of Figure 1;

Figure 3 is a vsectional view showing a modification of Figure 1 Figure4 is a section at the line 4-4 of Figure 3; and

Figure 5 is a sectional View showing a further modification.

Like parts are indicated by like symbols throughout the specificationand drawings.

Referring'to the drawings,`A generally indicates a food storage cabinetincluding an insulated back wall I, insulated side walls '2, aninsulated top wall 3,` an insulated bottom wall 4, and an insulatedintermediate partition 5. The above mentioned walls and partitions`define two storage. compartments which are separated from and insulatedfrom each other. i is an insulated door for the upper compartment and lan insulated door for the lower compartment. Thus the two. storagecompartments are insulated from each other and. from the, outside air.Any Suitable gasketmg or sealing means 8 may be employed., it beingunderstood that the details of the walls.I doors and sealing means donot of themselves form part of the present invention. Any suitable meansmay be employed for limiting to a mini.- mum heat transfer between theinside of the compartments and the outside air, and between they twocompartments.

For convenience, the uppercompartment 15in.- dicated as B and the lowercompartment as C'. Located below the lower compartment C 'isv anuninsulated space D for the condensing unit.

The upper storage compartment B is preferably held at a relatively hightemperature, as from 35 to 45 degrees Fahrenheit. TheA interior of thecompartment C may be maintained at a tem-r perature substantially belowfreezing, as from 0 to l0 degrees in order lto adapt it for quickfreezing and for cold storage of frozen goods.

In the form of Figures l and following adual refrigerating system isemployed having two separate refrigerant condensing units, with eva.1io'` rators in circuit with each unit, there being' thus a complete andindependent refrigeratingv system for each of the abovementioned storagecorn-A partments.

Referring to the details of the compartmentsd it is advantageous toemploy ar liner or sleeve of sheet metal for each compartment, withevapo-` rator coils on the exterior of each such sleeve, in heattransfer relationship therewith. In connection with the uppercompartment B is indicated a sleeve including a vertical rear wall I I,side wall I2, a top wall I3 and a bottom wall I4. l5 indicates anevaporator coilv which may extend about three sides of the liner' orsleeve thus formed, namely about the rear wall II and each of the sidewalls I2. The length of the coil and the area of walls with which it isin Contact may be varied to cause the refrigerant to be evaporated atthe desired temperature, preferably somewhatv above freezing, to preventfrost and to minimize dew formation on the walls, and to insure asuff'lciently vhigh relative humidity to prevent dehumidiflcation ofstored food.. The storage space of the compartment B is bounded at thebottom by an insulating food storage shelf I6 which is Shown assupported several inches above the bottom wall I4, of the upper sleeve.It is convenient to identify the space belowvthe insulating food shelfas the ice cubefOrming-andstOrage commeans and to design the gapfrom'shelf to wall partment E. In the compartment E is illustrated ashelf including an evaporator coil I'I, this coil orV evaporator beingin series with the evaporator I5. A restrictor 4I is interposed in theline 40 between evaporator I5 and evaporator I'I,-to reduce refrigerantpressure on evaporator II, which is thus made effective to freeze thecontents of any suitable ice cube tray or trays I 8. Positioned belowthe evaporator II is any suitable defrosting.

pan I9. Any suitable gap or gaps 2n may be ernployed between theinsulating shelf I6 and the side walls and door of the compartment B.This air gap provides a connecting vapor path or paths between thecompartment E and the compartment B, to permit excess water vapor to beVwithdrawn from the air inY compartment B. The storage shelf I6 may bepermanently fixed in relation ,v

to the upper sleeve, with suitable'gapsY or apertures provided, or itmay be removably mounted air gap. It will be understood however thatany.

other suitable means may be employed for maintaining the desiredcontrol.Or, it may be advantageous to omit any such variable control to producethe desired average condition.

vIn compartment C is a liner sleeve toplwall 28., Asinthe'case ofV theupper sleeve,

anyfsuitable evaporator .coil 29 Vmay extend about- Ythe sleeve," beingY'preferably exterior thereto but Yivnfheat transfer relationship.therewith..V The length and shape of the coil may be varied to suit.desired conditions but it may advantageously ex-V tend about the walls25, 26 Yand 28,. beingpref-rI erably omitted from'the bottoml wall lI.H

' With reference to the refrigerantY condensingunit, Vanysuitable meansmay be used.Vv VThe par-- ticlar .mechanisms -herein illustrated,however,

are ofthe mechanical type. With reference to their details, twocompressorsV are employed, 33

yfor the lower sleeve and 30a for the upper sleeve.-

suitablemeans may be employed for Vfeeding refrigerant. .Thelower-sleeve, is thus cooledto-a temperature from zero to plus 15degrees Fahrenheit, and the evaporated refrigerant returns by thesuction Yline 34 to thecompressorf30. "35 indicates any suitable motorfor'the compressor ,'30, which may be controlledby any suitable ther-Vmostatically operable switch 36, which may for, example include the bulb31 in the-compartmentt'xv Y Y Q Y' f Tracing the circuit for the uppersleeve, the liquidV refrigerant is 'delivered through the restrictortube 33a to the Vevaporator I5,'cooling that sleeve to a temperaturebetween 35 and 45 degrees. Preferably the refrigerant is evaporated atsuch a pressure and corresponding temperature Yin evaporator I5, thatthe surface Aof the upper sleeve is kept at or above freezing, thuspreventing the formation of frost andgminirniz-r includingVY the backwall 25, sidewalls 26, bottom wall 21 and.

.4 ing deposit of dew on the walls. Refrigerant from the evaporator I5flows through the return passage 4I) to any suitable restriction 4I,which causes a further pressure drop and consequent temperature drop inthe refrigerant which thereafter flows through the passage 42 to theevaporator 'I'I and there evaporates at a temperature low enough tocause the freezing of ice cubes or other material in the compartment E.The evaporated refrigerant then returns along the return duct 43 to thecompressor 30a. 44 indicates Va motor'for the compressor 30a, this motorbeing controlledby any suitable means such as for example the thermallyoperable switch 45 associated with the bulb 46 located at any suitablepoint in the upper compartment.

With reference to Figure 1 it will be understood that the motors 35 and44 may be employed to drive fans which circulate air through theindividual condensers 32 and 32a, or a chimney, at therear. oftheenclosing structure may beVV used. to. create an air.. current. throughthe.

condenser. In the form of Figure 5 a double circuit condenser 50 isillustrated whichincludes separate condenser coils 5I and 52, onev beingin 's circuit with the compressor 30 and the other with the vcompressor30a, but-both coils associated.

with a single fin structure. Y

' itwill be understood that under some circumstances it may be placed atthe topor the side of the compartment, with any suitable enclosure meanslimiting interchange ofV air between compartments B and E throughconvection currents, but making possible the free movement of watervapor between the compartments. f

. It v.will be realized that, Whereas, a practical "andi operativedevice is described and illustrated,

nevertheless many changes may be made in the size, shape, number andYdisposition of* parts without departing from the spirit oftheinvention. `.Therefore Ythe description. and drawings Y are tov be takenasin abroad sense illustrative or diagrammatic ratherlthan as limitedVto the precise showing. Y

The use and operation of the invention are as follows:

` The, domestic refrigerator -of the usual type has an evaporator"serving'both to cool the food storage space andto freeze ice. To freezeice the. evaporator must operate at aY refrigerant temperature so low as`to produce excessively dry airy The .relative humidity of the air towhich food is exposed may run from 20 to 40% which dehydrates meats,fruits and vegetables.

.To-avoid that dehydration it is the practice with some to cool thespace by` means of a refrigerated liner surface,` the cool area beingsufciently great so that the sleevey temperature need be only a fewdegrees below the wanted space temperature, witha minimum of around 32degree's. perature` during *off-cycles of the 'condensing unit due toheat leakage'through insulation to.

the liner wall; Itmayrlse to 40 degrees or above. By this meansV muchless moisture is condensed the relative humidity is therefore high;

j' Moisture entering with new air admitted whenY the door is vropenedwill condense as dew largely lon the coldest surfacesthe liner wallduring the 'on-cycles-and will'partly'or wholly evaporate duringoff-cycles when thewall is warm. Theiextent ofthe evaporation will bevlimited by This cold wall will assume a higher temthe time betweenonrcycles-,andthe relative vapor pressures between water on the coldwall and water in the air.

Should the cold Vwall rise to 40 degrees the vapor pressures Ywill cometo balance at 100% humidity, providing suflicient time elapses forevaporation between on-cycles. Actually 'the cold wall may exceed 40degrees.

With air at such high humidity there is certain to be condensation ofmoisture on Shelves and stored food at times when the temperature of thewet Wall is above that of the shelves and stored food. This creates anunsanitary condition and causes deterioration of meats and other foods.Another fault is that in humid weather sufficient moisture may enterwith incoming air to cause Water to condense on and run down the sidewalls and pool on the liner floor. This also is unsanitary.

In our refrigerator weuse the cold wall means for space cooling, withthe refrigerant coil external to but in thermal contact with the sleeve.To correct the faulty conditions mentioned we use the colder surface ofthe ice freezing evaporator to condense such water vapor as would causea humidity above, say 85%.

We place the refrigerated ice cube freezing shelf near the floor of theliner and locate a storage shelf of W heat conductivity immediatelyabove it. This storage shelf is dirnensioned t0 give an open space onall sides to permit water vapor to pass from the upper storage chamberto the cold shelf space.

AWe place the shelf at the bottom of the liner to prevent airinterchange between the two spaces by convection, the colder airsurrounding the ice freezing shelf being colder and there-fore denser.Water vapor, however, is free to pass downward under a head set up bythe differential in vapor pressures above and below, and this vapor owis controlled in amount by the size of the openings provided between thelower food shelf and surrounding walls,` as Well as by the refrigeranttemperature maintained in the ice freezing coil.

The ice freezing coil temperature, selected for purposes both ofcontrollingv humidity and of freezing ice at the required rate,isobtainecl by interposing a Xed restrictor lbetween the space coolingcoil and the ice freezing coil, resulting in a temperature of sleevesurface at or slightly above 32 degrees and in the ice coil of from 10to degrees, These vary during the cycle and with the conditions ofloading. By this construction we find it readily possible to hold therelative humidity at from 60 to 85% under widely varying ambient airconditions. At such humidities the liner wall may at times be moist whendoor openings are frequent in humid weather but at no time does it rundown the wall or deposit on shelves or food.

Food is not dehydrated and open storage of food is made possible,avoiding the loss of space occasioned by the use of covered containers.

It is not essential that the ice freezing shelf be located at the bottomof the food storage chamber. An insulating housing around an icefreezing shelf or shelves at top or side, so arranged as to preventinterchange of air by convection currents but permitting vapor movement,will give the same control of humidity.

The refrigerator described may be made alone or we may'combine it with asecond food compartment, all within one insulated housing, refrigeratedwith a second expansion coil and condensing unit, holding a temperaturebelow freezing for storage of frozen foods. In this case the tworefrigerating systems are wholly separate and independent in operation.

Or we may use a single condenser structure having a single iin assemblybut two separate refrigerant tube circuits, both in thermal contact withthe same fins, this z-circuit condenser serving two otherwiseindependent refrigerating means.

We may also utilize a single condensing unit to refrigerate both sleevesin accordance with the system described in our co-pending applicationSerial No. 583,925, filed March 21, 1945, now Patent No. 2,462,240,granted Feb. 22, 1949, on a two temperature refrigerator system, inwhich case the warmer sleeve is controlled as to humidity exactly asdescribed above.

Certain variations may be made in the design described above, as the useof a variable restrictoi` instead of the fixed restrictor between Ithespace cooling and the ice freezing evaporators. Or the opening betweenthe lower food shelf and l the outer walls may be varied in area bymeans such as dampers to permit the User t0 obtain variations inhumidity. We may also place the'ice freezingl shelf at the side or topof the food storage compartment, with an enclosure limiting orpreventing cold air leaving the ice freezing compartment but maintainingthe free movement of water vapor. Such variations are within the scopeof this patent application.

We claim:

1. In a domestic refrigerator having two storage chambers thermallyinsulated from each other and from the outside, a single work chamber,two in dependent refrigerant condensing units in said work chamber,common means for maintaining a cooling circulation of air past both saidcondensing units, an evaporator eifective in each storage chamber, twoindependent refrigerant circuits each including one of said evaporatorsand one of said condensing units, and an ice freezing evaporator, in oneof said storage compartments, in series with ,one of said firstmentioned evaporators.V

2. In a refrigerator including a cabinet having two storage chambersthermally insulated from each other and from the outside, a single workchamber, two independent refrigerant condensing units in said workchamber. common means for maintaining a cooling circulation of air pastboth said condensing units, an evaporator effective in each storagechamber, two independent refrigerant circuits each including one of saidevaporators and one of said condensing units, and

an ice freezing evaporator, in one of said storage compartments, inseries with the evaporator of the same storage compartment.

3. In a refrigerator including a cabinet having two storage chambersthermally insulated from each other and from the outside, a single workchamber, two independent refrigerant condensing units in said workchamber, common means for maintaining a cooling circulation of air pastboth said condensing units, an evaporator effective in each storagechamber, two independent refrigerant circuits each including one of saidevaporators and one of said condensing units, an ice freezing evaporatornear the bottom of one of said storage chambers, in series with theevaporator of that chamber, and insulating partition means, in saidstorage chamber, above said ice freezing evaporator, adapted to defineanice compartment and a food storage compartment within that chamber,there being communication between the twoV compartments .thus formed,adapted to provide water vapor transfer without air transfer between thecompartments.

4. In a refrigerator having two storage chambersv thermally insulatedfrom'each other and from the outside, a single work chamber, twoindependent Vrefrigerant condensing units in said work chamber,commonmeans for maintaining a cooling circulation of air past both saidcondensing units, an evaporator effective in each storage chamber, twoindependent refrigerant circuits each including one of said evaporatorsand one of said condensing units, an ice freezing evaporator near thebottom of one of said storage chambers, in series with one of said firstmentioned evaporators, insulating partition means, in Y inside surfaceof said compartment, anice cube shelf within the compartment, anevaporator for said shelf, in series with and following said rstmentioned evaporator, a restrictor between said evaporators, adapted toreduce the pressure Aand temperature of the ice cube evaporator belowthe pressure and temperature of the first mentioned evaporator, and aninsulating partition defining an ice cube'shelf zone within thecompartment but adapted to permit communication' between that zone andthe compartment, and means for controllingrsaid communication. v

6. In a domestic refrigerator system, a food storage compartment, anevaporator adapted to cool the upper inside surface of saidVcompartment, an ice cube shelf located near the bottom of thecompartment, an evaporator for 'said shelf,

in series with and following Vsaid rst mentioned evaporator, arestrictor between said evaporators, adapted to reduce the pressure andtemperature of the ice cube evaporatorbelow the pressure and temperatureof the first mentioned evaporator, means for delivering liquidrefrigerant to the first evaporator and for withdrawing the evaporatedrefrigerant from the ice cube evaporator, anda partition located abovethe ice cube shelf and extending toward but spaced from the walls of thecompartment, said partition having one or more gapsadapted to permitwater vapor flow from the space above to the space below said partition.

7. In a domestic refrigerator system, a food storage compartment, 'an`evaporator adapted to cool the upper inside surface of said compartment,an ice cube shelf located near the bottom of the compartment, anevaporator for said shelf, in series with and following said rstmentioned evaporator, a restrictor between said evaporators, adapted toreducerth'e pressure and temperature of the ice cube evaporator belowthe pressure and temperature of the first mentioned evaporator, meansfor delivering liquid refrigerant to the first evaporator and forwithdrawing evaporated refrigerant from the ice cube evaporator, apartition located above the ice cube shelf and extending toward butspaced from the walls of the compartment, said partition having one-ormore gaps adapted to permit Water vaporV ow from the space above to thespace below said partition, and

means for varying the eiiective cross sectional area of said gaps.

8. In a domestic refrigerator system, a food storage compartment havinga liner of heat conductive materiaLran evaporator constructed andarranged to cool the upper walls of said liner, a shelf adapted toreceive ice cube trays, located adjacent the bottom of said compartment,an

evaporator arranged to cool said shelf, means for REFERENCES CITED Thefollowing references are of record the file of this patent: Y.

STATES PATENTS vNumber Name Date 2,102,354 Chambers Dec. 14, 19372,133,958 Kalischer Oct. 25, 1938 2,196,527 Hainsworth Apr. 9, 19402,215,372 Howeth Sept. 17, 1940 Y V2,242,407 VTobey May 20, 1941`2,292,015 Schweller Aug. 4, 1942 Schweller May 18, 1943

